Depends on the fight and your group composition, both specs can perform well(although Holy parses higher thanks to Barrier not showing up in meters, oh boohoo).

But at this stage, even playing the fights that used to be "Play Disc mkay" as Holy (or vice versa), given all the nerfs to the contwnt even before the Aspect buff, it was moot. Now it's a joke.

The real question is, can your proest convinve 9 other people to click a Lightwell as a raid cooldown?